/* Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.flowable.cdi.impl.annotation;

import java.io.Serializable;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.util.HashMap;
import java.util.Map;

import javax.inject.Inject;
import javax.interceptor.AroundInvoke;
import javax.interceptor.Interceptor;
import javax.interceptor.InvocationContext;

import org.flowable.cdi.BusinessProcess;
import org.flowable.cdi.annotation.ProcessVariable;
import org.flowable.cdi.annotation.StartProcess;
import org.flowable.common.engine.api.FlowableException;

/**
 * implementation of the {@link StartProcess} annotation
 *
 * @author Daniel Meyer
 */
@Interceptor
@StartProcess("")
public class StartProcessInterceptor implements Serializable {

    private static final long serialVersionUID = 1L;

    @Inject
    BusinessProcess businessProcess;

    @AroundInvoke
    public Object invoke(InvocationContext ctx) throws Exception {
        try {
            Object result = ctx.proceed();

            StartProcess startProcessAnnotation = ctx.getMethod().getAnnotation(StartProcess.class);

            String name = startProcessAnnotation.name();
            String key = startProcessAnnotation.value();

            Map<String, Object> variables = extractVariables(startProcessAnnotation, ctx);

            if (name.length() > 0) {
                businessProcess.startProcessByName(name, variables);
            } else {
                businessProcess.startProcessByKey(key, variables);
            }

            return result;
        } catch (InvocationTargetException e) {
            Throwable cause = e.getCause();
            if (cause instanceof Exception) {
                throw (Exception) cause;
            } else {
                throw e;
            }
        } catch (Exception e) {
            throw new FlowableException("Error while starting process using @StartProcess on method  '" + ctx.getMethod() + "': " + e.getMessage(), e);
        }
    }

    private Map<String, Object> extractVariables(StartProcess startProcessAnnotation, InvocationContext ctx) throws Exception {
        Map<String, Object> variables = new HashMap<>();
        for (Field field : ctx.getMethod().getDeclaringClass().getDeclaredFields()) {
            if (!field.isAnnotationPresent(ProcessVariable.class)) {
                continue;
            }
            field.setAccessible(true);
            ProcessVariable processStartVariable = field.getAnnotation(ProcessVariable.class);
            String fieldName = processStartVariable.value();
            if (fieldName == null || fieldName.length() == 0) {
                fieldName = field.getName();
            }
            Object value = field.get(ctx.getTarget());
            variables.put(fieldName, value);
        }

        return variables;
    }

}
